DE69007259T2 - Container with capillary effect on the housing shell. - Google Patents

Description

The present invention relates to a container for liquids and gases for use in particular in satellites under low accelerations, in which the separating force generated by the surface tension is used to collect the liquid in a preferred region of the container without allowing gas to escape beyond this region.

The localization of liquids and their containment are two very important functions of containers that operate in zero gravity, where accelerations are minimal.

Currently, containers of this type are equipped with specific collection devices inside, designed to retain and drain the liquids.

The French patent application FR 2 484 961 relates to a surface tension container provided with such a collecting device. The collecting device described in this document makes it possible to localize the liquids in the vicinity of the liquid outlet provided on the spherical container. For this purpose, channels run along the meridian planes at a short distance from the inner wall of the container and open at one end into a collecting chamber located in the immediate vicinity of the liquid outlet opening. Various gas barriers (e.g. metal mesh) are provided on the collecting chamber and on the surface of the channels facing the inner wall of the container.

Another specific collection device is described in French patent application 2 486 624. In this document, the interior of the spherical container is lined with several supply blades arranged at a short distance from the inner wall of the container and opening into a cylindrical liquid outlet device. The latter is formed from a layered double structure with radially oriented inner blades and annular outer blades, the whole delimiting a central passage coaxial with the liquid outlet opening.

In a simpler way, US-3 486 302 shows a storage vessel enclosing a gas-liquid separating screen which is arranged at a certain distance from the inner wall near the vapor outlet and at a very short distance near the liquid outlet.

Another example of a partitioning device is presented in French patent application FR-2 283 390. This document shows a multiple partitioning system arranged inside the container in the form of compartments arranged in a fan-like manner. A liquid extraction line is provided at the base of the compartment.

In all of the above examples, the tapping function is implemented by a specific tapping device contained within the preferably spherically shaped container.

The present invention aims at realizing a container of simpler construction that can collect liquids particularly in zero gravity, as well as a container in which the limits of functionality are improved.

The object of the invention is in particular to facilitate the installation of a container in a system such as a satellite by allowing the use of very different external shapes, while simplifying manufacture by using substantially assembled, regularly shaped shell elements, which leads to a reduced mass since the use of a liquid expulsion device (DEL) is not necessary.

The objects are achieved according to the invention by a container of the type mentioned at the beginning of the description, which is characterized by:

- a first outer shell element which has a regular shape without corners and edges and has at one end a surface section S with radius of curvature r, which has a concave shape on the side of the liquid,

- a second, inner shell element which is connected to the first element, has a convex shape on the side of the liquid, has a regular shape without corners and edges and comprises a surface section S', a region of which almost touches the surface section S in the preferred region which forms the overall narrowest region lying between the surface sections S and S', the surface section S' having a radius of curvature r' which is smaller than the radius of curvature r at least at the level of the narrowest region, and

- at least one liquid removal element which opens into the narrowest region between the surface sections S and S', such that the liquid passes through a capillary action of the shell is maintained in the narrowest region between the first and second shell elements.

The two shell elements can have different shapes as long as the continuity of their surfaces is maintained i.e. as long as they have neither corners nor edges. These elements can, for example, be formed starting from a spherical or ellipsoidal shape.

The container can also be essentially toroidal.

Since the special shape of the first and second shell elements forms a liquid expulsion system without the addition of further elements, the structure of the container can be greatly simplified and its mass reduced. In addition, the container according to the invention can lead to a significant reduction in space requirements, especially when used in groups.

In order to enable more difficult tasks, in particular when the accelerations are strong, which tend to slow down the expulsion of the liquid, or when high flow rates are desired, the container with the specific configuration according to the present invention can advantageously - but not necessarily - have a liquid expulsion device arranged near the withdrawal element in the narrowest area. In a container with a bowl capillary effect according to the invention, provided with a liquid expulsion device, capillary forces are used whose density is greatly increased compared to that of the majority of known containers.

The liquid expulsion device can, for example, consist of perforated sheets oriented radially with respect to the shells; however, the device can also be formed of perforated sheets oriented substantially parallel to the surfaces in the contact area of the two shells.

The perforated sheets of the liquid expulsion device (DEL) enhance the capillary effect due to the container geometry, which is a significant improvement compared to containers with DEL, where the shape does not contribute to holding the liquids.

Without departing from the scope of the invention, the liquid expelling device can be a combination of the two above-mentioned embodiments, i.e. it can be formed by joining perforated metal sheets oriented radially or circumferentially according to the two aforementioned vertical directions.

The distance between the sheets is variable. It is smaller the smaller the distance to the liquid extraction point.

Other features and advantages of the present invention will become apparent from the following description, which refers to the accompanying drawings. In these drawings:

- Fig. 1 shows a section through a container shell according to a first embodiment of the invention,

- Figs. 2 to 4 and 5A, 5B each show sections through several other embodiments of the container according to the invention,

-Figs. 6A and 6B show a container according to the invention in section along the line VI-VI of Fig. 1, the upper half-shell of Fig. 6A showing a container provided with a liquid expulsion device with equidistant radial plates, and the lower half-section of Fig. 6B showing radial plates with variable spacing,

-Figs. 7A and 7B show a sectional view analogous to that of Figs. 6A and 6B, whereby the upper half-section in Fig. 7A shows a container with interrupted circular sheets and the lower half-section in Fig. 7B shows a container with continuous circular sheets,

-Figs. BA and 8B show a section along the line VIII-VIII of Fig. 3, which is analogous to the section of Figs. 6A and 6B, but which shows in the upper part in Fig. BA a combined device with equidistant radial plates and in the lower part shown in Fig. 8B a combined device with radial plates with variable spacing,

-Fig. 9A, 9B, 9C show in section the filling of the different compartments of a liquid expulsion device with non-equidistant radial plates,

-Fig. 10A shows in section the filling of the different compartments of a liquid expulsion device with equidistant radial plates,

-Fig. 10B is a section analogous to the upper half section of Fig. 6A, showing the length development of the radial sheets with constant spacing limited fan,

- Fig. 11 and 12 are sectional views analogous to those of Fig. 7A and 7B, but showing two different distributions of the circular plates and two different locations of the liquid extraction line,

- Fig. 13 is a sectional view similar to that of Figs. 7A and 7B, showing a special liquid extraction line,

- Fig. 14 is a schematic sectional view showing two nested containers according to the invention and

- Fig. 15 is a schematic sectional view showing a conventional spherical container nested in a container according to the invention.

Figures 1 to 5 each show a container formed from two shell elements, a larger, concave element 1 and the other element 2 which lies inside the first and is convex towards the interior of the container. The two shell elements 1, 2 are arranged so that they define between them an area 3 in which they have almost touching surfaces S, S' in order to keep the liquid contained in the container in this area by capillary action. In this area 3 the radius of curvature r' of the surface S' is smaller than the radius of curvature r of the surface S.

A removal element 5 for the liquid held in the area 3 is provided. This pipe-shaped element opens into the narrowest part of the almost contact area 3 between the shells 1 and 2.

Fig. 1 shows a first embodiment of the invention, in which the shells 1, 2 are both spherical.

The radius r' of the inner sphere 2 is smaller than the radius r of the outer sphere. The centers C and C' of both spheres do not coincide, so that the almost contact area is formed in which the liquid is held by the effect of surface tension in the case of virtually vanishing acceleration.

According to a second embodiment of the invention shown in Fig. 2, the first shell element is hemispherical in a first region Ss and is extended at its two ends by a cylindrical surface Sc₁, Sc₂. The second shell element 2 has a spherical surface with radius r' and center C'. One end of this spherical surface 2 is connected to the lower end of a region of smallest height of the cylindrical surface Sc₁ of the first shell element 1, whereas the second end of the inner sphere 2 almost touches the lower end of a region of greater height of the cylindrical surface Sc₂ of the first shell element 1 to form the region 3 for holding the liquid 7. Since in this region the radius of curvature r of the first shell element 1 is infinite, the above-mentioned feature with regard to the radii r and r' is of course still fulfilled. Finally, a removal element 5 is provided, which opens into the closest contact area between the first and the second shell element 1, 2.

As can be seen in Fig. 2, the small cylindrical surface Sc1 is preferably connected to the inner shell 2 by a small rounded section which avoids the formation of an angular transition in which a residual volume of liquid difficult to tap would remain.

Fig. 3 shows a design that differs from that shown in Fig. 2 only in the relative arrangement of the shell elements and the fact that the outer shell 1 is axially symmetrical to the axis XX'. The inner shell 2 is a hemisphere whose center is not on the axis of symmetry XX' of the first shell, thereby forming the near-contact area 3 (in the left part of Fig. 3).

Fig. 4 differs from Fig. 2 only in the shape of the inner shell 2, which in this embodiment is ellipsoidal.

Fig. 5A shows a substantially toroidal container, each half-section of which has, for example, a shape identical to that of Fig. 2. In this case, several extraction elements 5 are necessary in order to achieve a better distribution of the extraction over the entire toroidal container. However, there can also be a single extraction line if the container is formed from two toroidal surfaces offset in their axes, as shown in the variant of Fig. 5B.

As in the case of Fig. 2, the containers of Figs. 4, 5A and 5B preferably have a rounded inner connecting portion between the inner shell 2 and the shell 1 in the inner transition area, which does not interact with a removal element 5.

Without departing from the scope of the invention, a container according to one of the embodiments described above can be provided with a liquid expulsion device (DEL) 4, as shown for example in Figs. 6A, 6B, 7A, 7B, 8A, 8B.

Two first forms of DEL are shown in Fig. 6A and 6B

The upper half-section of Fig. 6A shows a DEL in the form of regularly spaced and radially oriented perforated sheets 41 with respect to the (or a) axis of symmetry of the first shell element 1. These sheets are fixed between the two shell elements in the contact area 3 in which the liquid is held and only rise above a fraction of the height of the container. They thus reinforce the capillary effect caused by the geometry of the container, which represents a noticeable improvement compared to containers with DEL whose shape does not contribute to holding the liquids.

The lower half-section of Fig. 6B represents a configuration quite similar to the previous one, since the only difference is the distance between the perforated sheets 41, which is no longer constant but variable. More precisely, the distance decreases in the same way as the distance between the first and second shells. In the two cases mentioned above, the extraction element 5 is preferably fixed in the area where the capillary effect is strongest, i.e. where the sheets are closest to each other.

Advantageously, the diameters of the holes in the radial plates 41 are smaller the closer the removal element 5 is.

Figs. 9A, 9B, 9C and 10A, 10B help to understand the operation of the two liquid expelling devices described above.

Towards the end of the service life, i.e. when the mass of the liquid 7 in the tank is low, the liquid 7 no longer completely covers the compartments 61, 62, 63 formed between the radial plates 41, in particular the compartment 61 where the distance between the plates is the smallest, so that the compartment 61 is emptied first. The emptying must then be carefully monitored since the compartment 61 must under no circumstances be completely emptied in order to avoid any escape of gas through the extraction line 5. The level shown in Fig. 9A is the minimum permissible level.

In zero gravity, compartment 61 fills first (Fig. 9B) by drawing from the adjacent compartment 61, which in turn draws from the following compartment 63. This is because the meniscus formed by compartment 61 has a capillary force Δp1 greater than the capillary force Δp2 of compartment 62, since the distance between walls 41 is smaller and therefore the local curvature of the meniscus is greater. The same phenomenon occurs between compartments 62 and 63; until the final equilibrium shown in Fig. 9C is reached. The rate of refilling is related to the pressure losses of the liquid at the holes 44 broken in the sheets 41.

With the help of Figs. 10A and 10B, the phenomenon of refilling of the compartment 61 connected to the extraction line 5 can be explained in the case where the sheets 41 are equististant. Here, of course, the same physical law applies as in the previous case, with the difference that a stronger capillary effect in compartment 61 comes from the fact that the radially measured length La, Lb, Lc ... between the shells 1 and 2 becomes smaller the closer one gets to the extraction line 5 through the compartments 64, 63, 62, 61. The local curvature of the meniscus in compartment 61 is therefore greater than in compartment 62, which in turn is greater than that of compartment 63, etc.

According to another embodiment of the invention, shown in Figs. 7A and 7B, the liquid expelling device DEL consists of circumferential perforated sheets 42, i.e. sheets that are oriented essentially parallel to the shell elements in the contact area 3.

As can be seen in the upper half-section of Fig. 7A, the perforated sheets 42 can be interrupted. However, they can also be continuous, as shown in the lower half-section of Fig. 7B. These sheets 42 are eccentric, so that the distance between sheets or between sheet and bowl decreases towards the extraction line 5. This opens into the one of the compartments 31 to 33 in which the capillary force is greatest, that is, for example, into the compartment 31, which has the smallest length measured in the radial direction and therefore the greatest curvature and consequently the strongest capillary effect.

The extraction line 5 can open at a point 53 close to the inner shell (Fig. 12) or at a point 51 close to the outer shell 1 (Fig. 11), depending on the structure of the DEL.

The same physical principle applies here as for the DEL with radial plates. As a result, towards the end of the emptying of the container, the compartment into which the extraction line 5 opens and in which the menisci have the greatest capillary force is the first to empty. Of course, when operating under acceleration due to the drives of the vehicle equipped with the container, the emptying must be stopped before the last compartment is completely empty in order to avoid gas leakage. In weightlessness, the stronger capillary force allows a progressive refill of the corresponding compartment, i.e. the most empty compartment.

Without departing from the scope of the invention, a DEL is proposed in which the above-described designs are combined, i.e. which is simultaneously formed from radial perforated sheets 41 (equidistant or with a variable spacing) and from perforated circumferential sheets 42. An exemplary embodiment is given in Figs. BA and SB, which show radial sheets with a constant spacing in the upper area (Fig. 8A) and sheets 41 in the lower area (Fig. 8B) which are closer to one another the smaller the distance to the extraction line 5, with an additional perforated circumferential sheet 42 being arranged between the shells 1 and 2.

As shown by way of example in Fig. 3, an additional perforated sheet 43 can be placed locally above the grid formed by the perforated sheets 41 and 42 in order to define a volume V to which the extraction line 5 is connected. This volume V serves as a buffer. In other words, this volume can be used to extract liquid, but must then It must be refilled in a phase of quasi-weightlessness before it can be used again.

If the DEL consists of several compartments 31, 32, 33, the extraction line can be provided with several holes 51, 52, 53 of graduated size, which open into all the compartments 31, 32, 33 (Fig. 13) or some of the compartments 31, 32, 33. Advantageously, the hole 53 with the largest diameter opens into the compartment 33 from which the liquid is to be drawn first and conversely, the smallest hole 51 opens into the compartment 31 from which the liquid is to be drawn last. The diameters of the openings 53, 52, 51 of the extraction line 5 therefore decrease in the order of drawing off the liquid from the various compartments 33, 32, 31.

Figures 14 and 15 show the reduced space requirement of an arrangement of two containers, at least one of which is according to the invention, i.e. which comprises a first outer shell element 1 concave towards the liquid side and a second outer shell element 2 convex towards the liquid side.

Often, several containers for liquids and gases are needed next to each other, e.g. in the case of a dual-fluid drive, where it makes sense to store the two fuels in two different containers. The conventional containers, e.g. spherical ones, require a considerable amount of space.

With the containers according to the invention, in particular with containers as shown in Figs. 2, 4, 5A, 5B, a compact arrangement can be achieved by nesting two or more containers on top of one another.

In Fig. 14, two containers A, A' are shown, which correspond to the design of Fig. 2. The container A', which is identical to the container A and comprises elements whose reference numerals are provided with a prime, has an outer shell 1', the concave curvature of which faces the liquid of the container A', and is nested in the container A and is located under the inner shell 2 of the container A, the convex curvature of which faces the liquid. Similar compact arrangements can be achieved, for example, with containers of torus shape.

Fig. 15 shows the connection of a container A according to the invention, which has a withdrawal element 5, to a container B, which has a withdrawal element 5'. In this case, however, the container B has a conventional spherical shape and can be provided with a DEL. The improvement in space requirements is due to the fact that the spherical shell of the container B can be accommodated within the inner shell 2 of the container A, the convex curvature of which faces the liquid contained in the container A.

Claims (17)

1. Container for liquids and gases for use in particular in satellites under low acceleration, in which the separation force generated by the surface tension is used to collect the liquid (7) in a preferred area (3) of the container, without allowing gas to escape beyond this area, characterized by: - a first, outer shell element (1) which has a regular shape without corners and edges and has at one end a surface section S with radius of curvature r which has a concave shape on the side of the liquid, - a second, inner shell element (2) which is connected to the first element (1), has a convex shape on the side of the liquid, has a regular shape without corners and edges and comprises a surface section S', one area of which almost touches the surface section S in the preferred area (3) which forms the overall narrowest area lying between the surface sections S and S', the surface section S' having a radius of curvature r' which is smaller than the radius of curvature r at least at the level of the narrowest area (3), and - at least one liquid removal element (5) which opens into the narrowest region (3) between the surface sections S and S', such that the liquid is drawn off by a capillary action the shell is held in the narrowest region (3) between the first and second shell elements (1, 2). 2. Container according to claim 1, characterized in that the second shell element (2) is formed from a hemispherical shape. 3. Container according to claim 1, characterized in that the second shell element (2) is formed from an ellipsoidal shape. 4. Container according to claim 1, characterized in that it is substantially toroidal. 5. Container according to one of the preceding claims, characterized in that it additionally comprises a liquid expulsion device (4) which is mounted in the vicinity of the removal element (5) in the narrowest region (3). 6. Container according to claim 5, characterized in that the liquid expelling device (4) consists of radially oriented perforated metal sheets (41). 7. Container according to claim 6, characterized in that the radial plates (41) are equally spaced from one another. 8. Container according to claim 6, characterized in that the radial sheets (41) lie closer to one another, the smaller the distance to the removal element (5). 9. Container according to claim 5 or claim 6, characterized in that the liquid expelling device (4) comprises at least one circumferential perforated sheet (42) which is oriented substantially parallel to the surface sections S and S' in the region (3) of the almost contact of the surfaces. 10. Container according to claim 9, characterized in that each circumferential sheet (42) arranged at a given distance from one of the two surface sections S, S' is one-piece. 11. Container according to claim 9, characterized in that each circumferential sheet (42) arranged at a given distance from one of the two shells (1, 2) is formed from several parts. 12. Container according to one of claims 5, 9, 10 or 11, characterized in that the radial sheets (41) and the circumferential sheets (42) are arranged in such a way that the distances between sheets in the region (3) of the almost contact of the surfaces decreases the more the smaller the distance to the tapping point of the removal element (5) is. 13. Container according to one of claims 6 to 8, characterized in that the sheets (41) are provided with holes (44) whose diameter changes in the same direction as the distance of the sheet (41) from the extraction line (5). 14. Container according to claims 6 and 9, characterized in that an additional perforated sheet (43) is arranged at the end of the grid network formed by the radial sheets (41) and the circumferential sheets (42) in order to define a buffer volume into the interior of which the removal element (5) opens. 15. Container according to one of claims 8 to 14, characterized in that the removal element (5), which is arranged in an area with a predominant angular effect (effet de coin), opens into the compartment defined by at least one radial or circumferential perforated sheet (41, 42) and at least one of the surface areas S and S', in which the capillary force is greatest. 16. Container according to one of claims 9 to 12, characterized in that the removal element (5) is provided with several openings (51, 52, 53) with stepped, mutually different diameters, each of which opens into different compartments (31, 32, 33) which are separated by the circumferential sheets (42), the diameters of the openings (53, 52, 51) decreasing in the order in which the liquid is tapped in the different compartments (33, 32, 31). 17. Arrangement of containers according to one of claims 1 to 16, characterized in that the various containers (A, A') are nested one inside the other, the first outer shell element (1') of one container (A') being in the immediate vicinity of the second, inner shell element (2) of another container (A) of the container arrangement (A, A').